/* -------------------------------------------------------------------------
 *
 *	md5.cpp
 *
 *	Implements	the  MD5 Message-Digest Algorithm as specified in
 *	RFC  1321.	This  implementation  is a simple one, in that it
 *	needs  every  input  byte  to  be  buffered  before doing any
 *	calculations.  I  do  not  expect  this  file  to be used for
 *	general  purpose  MD5'ing  of large amounts of data, only for
 *	generating hashed passwords from limited input.
 *
 *	Sverre H. Huseby <sverrehu@online.no>
 *
 *	Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 *	Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *	  src/common/backend/libpq/md5.cpp
 *
 * -------------------------------------------------------------------------
 */

/* This is intended to be used in both frontend and backend, so use c.h */
#include "c.h"
#include "securec.h"
#include "securec_check.h"

#include "libpq/md5.h"

/*
 *	PRIVATE FUNCTIONS
 */
/* Notice: md5.cpp can not compile and link to kernel(backend).
 * So we can't use securec_check, securec_check_ss and elog.
 */
#define SECUREC_CHECK(rc) securec_check_c(rc, "", "")
#define SECUREC_CHECK_SS(rc) securec_check_ss_c(rc, "", "")

/*
 *	The returned array is allocated using malloc.  the caller should free it
 *	when it is no longer needed.
 */
static uint8* createPaddedCopyWithLength(const uint8* b, uint32* l)
{
    uint8* ret = NULL;
    uint32 q;
    uint32 len, newLen448;
    uint32 len_high, len_low; /* 64-bit value split into 32-bit sections */

    len = ((b == NULL) ? 0 : *l);
    newLen448 = len + 64 - (len % 64) - 8;
    if (newLen448 <= len)
        newLen448 += 64;

    *l = newLen448 + 8;
    if ((ret = (uint8*)malloc(sizeof(uint8) * *l)) == NULL)
        return NULL;

    if ((b != NULL) && (len > 0)) {
        int rc = memcpy_s(ret, sizeof(uint8) * len, b, sizeof(uint8) * len);
        SECUREC_CHECK(rc);
    }

    /* pad */
    ret[len] = 0x80;
    for (q = len + 1; q < newLen448; q++)
        ret[q] = 0x00;

    /* append length as a 64 bit bitcount */
    len_low = len;
    /* split into two 32-bit values */
    /* we only look at the bottom 32-bits */
    len_high = len >> 29;
    len_low <<= 3;
    q = newLen448;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    len_low >>= 8;
    ret[q++] = (len_low & 0xff);
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q++] = (len_high & 0xff);
    len_high >>= 8;
    ret[q] = (len_high & 0xff);

    return ret;
}

#define F(x, y, z) (((x) & (y)) | (~(x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & ~(z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
#define ROT_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

static void doTheRounds(uint32 X[16], uint32 state[4])
{
    uint32 a, b, c, d;

    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];

    /* round 1 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[0] + 0xd76aa478), 7);   /* 1 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[1] + 0xe8c7b756), 12);  /* 2 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[2] + 0x242070db), 17);  /* 3 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[3] + 0xc1bdceee), 22);  /* 4 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[4] + 0xf57c0faf), 7);   /* 5 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[5] + 0x4787c62a), 12);  /* 6 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[6] + 0xa8304613), 17);  /* 7 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[7] + 0xfd469501), 22);  /* 8 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[8] + 0x698098d8), 7);   /* 9 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[9] + 0x8b44f7af), 12);  /* 10 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[10] + 0xffff5bb1), 17); /* 11 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[11] + 0x895cd7be), 22); /* 12 */
    a = b + ROT_LEFT((a + F(b, c, d) + X[12] + 0x6b901122), 7);  /* 13 */
    d = a + ROT_LEFT((d + F(a, b, c) + X[13] + 0xfd987193), 12); /* 14 */
    c = d + ROT_LEFT((c + F(d, a, b) + X[14] + 0xa679438e), 17); /* 15 */
    b = c + ROT_LEFT((b + F(c, d, a) + X[15] + 0x49b40821), 22); /* 16 */

    /* round 2 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[1] + 0xf61e2562), 5);   /* 17 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[6] + 0xc040b340), 9);   /* 18 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[11] + 0x265e5a51), 14); /* 19 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[0] + 0xe9b6c7aa), 20);  /* 20 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[5] + 0xd62f105d), 5);   /* 21 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[10] + 0x02441453), 9);  /* 22 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[15] + 0xd8a1e681), 14); /* 23 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[4] + 0xe7d3fbc8), 20);  /* 24 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[9] + 0x21e1cde6), 5);   /* 25 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[14] + 0xc33707d6), 9);  /* 26 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[3] + 0xf4d50d87), 14);  /* 27 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[8] + 0x455a14ed), 20);  /* 28 */
    a = b + ROT_LEFT((a + G(b, c, d) + X[13] + 0xa9e3e905), 5);  /* 29 */
    d = a + ROT_LEFT((d + G(a, b, c) + X[2] + 0xfcefa3f8), 9);   /* 30 */
    c = d + ROT_LEFT((c + G(d, a, b) + X[7] + 0x676f02d9), 14);  /* 31 */
    b = c + ROT_LEFT((b + G(c, d, a) + X[12] + 0x8d2a4c8a), 20); /* 32 */

    /* round 3 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[5] + 0xfffa3942), 4);   /* 33 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[8] + 0x8771f681), 11);  /* 34 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[11] + 0x6d9d6122), 16); /* 35 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[14] + 0xfde5380c), 23); /* 36 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[1] + 0xa4beea44), 4);   /* 37 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[4] + 0x4bdecfa9), 11);  /* 38 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[7] + 0xf6bb4b60), 16);  /* 39 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[10] + 0xbebfbc70), 23); /* 40 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[13] + 0x289b7ec6), 4);  /* 41 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[0] + 0xeaa127fa), 11);  /* 42 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[3] + 0xd4ef3085), 16);  /* 43 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[6] + 0x04881d05), 23);  /* 44 */
    a = b + ROT_LEFT((a + H(b, c, d) + X[9] + 0xd9d4d039), 4);   /* 45 */
    d = a + ROT_LEFT((d + H(a, b, c) + X[12] + 0xe6db99e5), 11); /* 46 */
    c = d + ROT_LEFT((c + H(d, a, b) + X[15] + 0x1fa27cf8), 16); /* 47 */
    b = c + ROT_LEFT((b + H(c, d, a) + X[2] + 0xc4ac5665), 23);  /* 48 */

    /* round 4 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[0] + 0xf4292244), 6);   /* 49 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[7] + 0x432aff97), 10);  /* 50 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[14] + 0xab9423a7), 15); /* 51 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[5] + 0xfc93a039), 21);  /* 52 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[12] + 0x655b59c3), 6);  /* 53 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[3] + 0x8f0ccc92), 10);  /* 54 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[10] + 0xffeff47d), 15); /* 55 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[1] + 0x85845dd1), 21);  /* 56 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[8] + 0x6fa87e4f), 6);   /* 57 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[15] + 0xfe2ce6e0), 10); /* 58 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[6] + 0xa3014314), 15);  /* 59 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[13] + 0x4e0811a1), 21); /* 60 */
    a = b + ROT_LEFT((a + I(b, c, d) + X[4] + 0xf7537e82), 6);   /* 61 */
    d = a + ROT_LEFT((d + I(a, b, c) + X[11] + 0xbd3af235), 10); /* 62 */
    c = d + ROT_LEFT((c + I(d, a, b) + X[2] + 0x2ad7d2bb), 15);  /* 63 */
    b = c + ROT_LEFT((b + I(c, d, a) + X[9] + 0xeb86d391), 21);  /* 64 */

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

static int calculateDigestFromBuffer(const uint8* b, uint32 len, uint8 sum[16])
{
    register uint32 i, j, k, newI;
    uint32 l;
    uint8* input = NULL;
    register uint32* wbp = NULL;
    uint32 workBuff[16], state[4];

    l = len;

    state[0] = 0x67452301;
    state[1] = 0xEFCDAB89;
    state[2] = 0x98BADCFE;
    state[3] = 0x10325476;

    if ((input = createPaddedCopyWithLength(b, &l)) == NULL)
        return 0;

    for (i = 0;;) {
        if ((newI = i + 16 * 4) > l)
            break;
        k = i + 3;
        for (j = 0; j < 16; j++) {
            wbp = (workBuff + j);
            *wbp = input[k--];
            *wbp <<= 8;
            *wbp |= input[k--];
            *wbp <<= 8;
            *wbp |= input[k--];
            *wbp <<= 8;
            *wbp |= input[k];
            k += 7;
        }
        doTheRounds(workBuff, state);
        i = newI;
    }
    free(input);
    input = NULL;

    j = 0;
    for (i = 0; i < 4; i++) {
        k = state[i];
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
        k >>= 8;
        sum[j++] = (k & 0xff);
    }
    return 1;
}

static void bytesToHex(uint8 b[16], char* s)
{
    static const char* hex = "0123456789abcdef";
    int q, w;

    for (q = 0, w = 0; q < 16; q++) {
        s[w++] = hex[(b[q] >> 4) & 0x0F];
        s[w++] = hex[b[q] & 0x0F];
    }
    s[w] = '\0';
}

/*
 *	PUBLIC FUNCTIONS
 */
/*
 *	pg_md5_hash
 *
 *	Calculates the MD5 sum of the bytes in a buffer.
 *
 *	SYNOPSIS	  #include "md5.h"
 *				  int pg_md5_hash(const void *buff, size_t len, char *hexsum)
 *
 *	INPUT		  buff	  the buffer containing the bytes that you want
 *						  the MD5 sum of.
 *				  len	  number of bytes in the buffer.
 *
 *	OUTPUT		  hexsum  the MD5 sum as a '\0'-terminated string of
 *						  hexadecimal digits.  an MD5 sum is 16 bytes long.
 *						  each byte is represented by two heaxadecimal
 *						  characters.  you thus need to provide an array
 *						  of 33 characters, including the trailing '\0'.
 *
 *	RETURNS		  false on failure (out of memory for internal buffers) or
 *				  true on success.
 *
 *	STANDARDS	  MD5 is described in RFC 1321.
 *
 *	AUTHOR		  Sverre H. Huseby <sverrehu@online.no>
 *
 */
bool pg_md5_hash(const void* buff, size_t len, char* hexsum)
{
    uint8 sum[16];

    if (!calculateDigestFromBuffer((const uint8*)buff, len, sum))
        return false;

    bytesToHex(sum, hexsum);
    return true;
}

bool pg_md5_binary(const void* buff, size_t len, void* outbuf)
{
    if (!calculateDigestFromBuffer((uint8*)buff, len, (uint8*)outbuf))
        return false;
    return true;
}

/*
 * Computes MD5 checksum of "passwd" (a null-terminated string) followed
 * by "salt" (which need not be null-terminated).
 *
 * Output format is "md5" followed by a 32-hex-digit MD5 checksum.
 * Hence, the output buffer "buf" must be at least 36 bytes long.
 *
 * Returns TRUE if okay, FALSE on error (out of memory).
 */
bool pg_md5_encrypt(const char* passwd, const char* salt, size_t salt_len, char* buf)
{
    size_t passwd_len = strlen(passwd);
    errno_t rc = EOK;
#ifndef WIN32
    if (unlikely(passwd_len >= SIZE_MAX - salt_len)) {
        return false;
    }
#else
    if (passwd_len >= SIZE_MAX - salt_len) {
        return false;
    }
#endif
    /* +1 here is just to avoid risk of unportable malloc(0) */
    char* crypt_buf = (char*)malloc(passwd_len + salt_len + 1);
    bool ret = false;

    if (crypt_buf == NULL)
        return false;

    /*
     * Place salt at the end because it may be known by users trying to crack
     * the MD5 output.
     */
    rc = memcpy_s(crypt_buf, passwd_len + 1, passwd, passwd_len);
    SECUREC_CHECK(rc);

    rc = memcpy_s(crypt_buf + passwd_len, salt_len + 1, salt, salt_len);
    SECUREC_CHECK(rc);

    rc = strcpy_s(buf, MD5_PASSWD_LEN + 1, "md5");
    SECUREC_CHECK(rc);

    ret = pg_md5_hash(crypt_buf, passwd_len + salt_len, buf + 3);

    rc = memset_s(crypt_buf, passwd_len + salt_len + 1, 0, passwd_len + salt_len + 1);
    SECUREC_CHECK(rc);
    free(crypt_buf);
    crypt_buf = NULL;

    return ret;
}
